Most prior art in the area of monolithic prisms for micro-display imaging have similar properties. Such patents describe a prism with three optically-active surfaces, which can be used with and without a corrector optic.
Recent developments in micro-display technology have created large-format, full-color micro-displays. A new near-eye optical imaging approach is needed to fully realize the size and resolution of these displays with wide fields of view and large eye pupils. Also to use such a device effectively in a system concept, the imaging device must allow a large range of diopter adjustment for comfort and must conserve power by not requiring digital image remapping of the displayed image.
Similar previous work employs a monolithic prism for presenting micro-display imagery to the eye in a compact, low-profile manner. These monolithic prisms utilize multiple internal reflections to image a micro-display to the eye. For example, U.S. Pat. No. 5,745,295 describes such an apparatus, including an image display device and an ocular optical system for displaying an image of the display device. While such known display image sources can scale to diagonal dimension of less than or equal to 15 mm, these known sources will have several performance flaws if scaled to image sources with a diagonal dimension of greater than 15 mm. This is due to the limited optical path associated with such known prism arrangements. Further, such prior art disclosures (e.g., U.S. Pat. No. 5,745,295) describe embodiments that have discontinuities in optical surface profiles which preclude scaling without extensive redesign.